JPS63240026A - Side etching - Google Patents

Abstract

PURPOSE:To increase the amount of side etching and decrease damage to the etched surface by a method wherein a substrate is arranged in a gas selectively etching the first layer by excitation while the substrate is irradiated with light exciting the etching gas from the second translucent layer side. CONSTITUTION:A substrate 1 is arranged in a gas selectively etching a first layer 2 by excitation through a second layer 3, a translucent layer, while the substrate 1 is irradiated with light 5 exciting the etching gas from the second layer 3 side. In other words, since the second layer 3 is translucent, the irradiated exciting light 5 reaches the side etching part and continuously excites the etchant gas near the etching surface during the side etching process. Through these procedures, the amount of side etching can be increased so that the etched surface may be made clean and smooth reducing damage to the surface.

Description

[Detailed Description of the Invention] [Summary] In side etching, in which the first layer is etched from the exposed portion of the first layer into the area of the second layer on the first layer, the second layer is etched. By making the etching transparent and exciting the etching gas in the etched area with light, it is possible to increase the amount of side etching, while reducing damage to the etched surface while obtaining a clean and smooth surface. It is.

[Industrial application field]

The present invention relates to a side etching method in which a first layer is etched from an exposed portion of the first layer into a region of a second layer above the first layer.

Etching is widely used in wafer processes for manufacturing semiconductor devices, and side etching, which is one of these techniques, expands the degree of freedom in designing semiconductor devices.

If the amount of side etching can be increased, the degree of freedom in design can be further expanded.

[Conventional technology]

FIG. 3 is a side view illustrating an example of a conventional method of side etching.

The side etching shown in the figure includes the first layer 2 made of SS on the substrate 1 whose surface is made of Si3N4, and the opening above it that exposes the first layer 2. In the second layer 3 having holes 4 and made of 5i02, wet etching is performed using the first layer 2 as a side etching target.

As the etching solution, KOH and +H20, which selectively etch Si in the above combination, are used.

The etching solution passes through the opening 4 and is etched by a chemical reaction.
wI2 is etched, but this etching is shown in Figure (b).
), side etching is achieved by spreading from just below the opening 4 to the area of the second layer 4.

Further, FIG. 4 is a side view illustrating another example of the conventional method.

The side etching shown in the same figure is carried out by dry etching using plasma generated by high frequency, for example by reaction etching, with the first layer 2 shown in FIG. This is done by reactive ion etching (RIE).

As the etching gas, CC1, which selectively etches Si in the above combination, is used. CCIA that occurred
The plasma and the ions generated together pass through the opening 4 and reach the first J' by chemical reaction and sputtering effect.
ef2 is etched, and this etching spreads from directly below the opening 4 to the area of the second layer 4 to achieve side etching, as shown in FIG.

[Problem that the invention seeks to solve]

However, in both of the conventional methods mentioned above, the etching liquid or plasma passes through the openings 4 to perform side etching, so as the amount of side etching (the depth of penetration into the area of the second layer 3) increases, the etching speed increases. There is a problem in that there is a limit to the amount of side etching that can be done because the etching stops when the amount of side etching decreases and reaches a certain size.

In addition, in the case of the former wet etching, the etching solution contaminates the surface it touches and the etched surface of the first layer 2 becomes rough, while in the case of the latter dry etching, the etching solution contaminates the surface it touches and the etched surface becomes rough. Although the surface is clean and smooth with little roughness, there is also the problem that the etched surface of the first layer 2 is damaged by the above-mentioned sputtering effect.

[Means for solving problems]

The above problem is caused by the fact that in the first layer on the substrate and the second layer on top of which a portion of the layer is exposed, the problem is that the exposed portion of the first layer enters the area of the second layer. When performing side etching to etch the first layer, the second layer is made transparent, the substrate is placed in a gas that selectively etches the first layer by excitation, and the etching gas is This problem is solved by the side etching method of the present invention in which exciting light is irradiated onto the substrate from the second layer side.

[Effect]

It is known that an etching gas also exhibits an etching effect when excited by light, and that this effect is a chemical reaction.

The present invention utilizes this phenomenon to effectively perform side etching.

That is, since the second layer is translucent, the irradiated excitation light reaches the side etching portion, so that the etching gas is continuously excited in the vicinity of the etched surface during side etching.

Therefore, in side etching using this method,
Even if the side etching amount increases, a substantially constant etching speed is maintained, and the side etching amount can be made much thicker than in the conventional method described in the previous example.

Also, since the action of the excited etching gas in this case does not have a sputtering effect, the damage to the etched surface of the first layer is much less than in the case of conventional dry etching.

Needless to say, as with conventional dry etching, the surface after etching is clean and smooth.

〔Example〕

Examples of the method of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a side view for explaining an embodiment, and FIG. 2 is a side view of a main part of an example of an apparatus for carrying out the embodiment. The same reference numerals indicate the same objects throughout the figures.

In the side etching shown in FIG. 1, No. 10N2 shown in FIG. 3, which was described in the example of the conventional method, is subjected to side etching. Here, the surface of the substrate 1 is made of Si3 N4, St
The thickness of the first lW2 made of XSiO is approximately 0.3 μm.
The thickness of the second layer 3 made of 2 is approximately 0.1 μm, and the size of the opening 4 is approximately 0.3 μm square.

Etching is performed as follows.

That is, in FIG. 1, the substrate 1 provided with the first and second wIs of 2.3 is placed in a C12 gas atmosphere at a pressure of 20 Torr, and the temperature of the substrate 1 is maintained at 100° C. at all times. Therefore, using a mercury lamp that emits ultraviolet light with a wavelength of around 340 nm,
The excitation light 5 made of the ultraviolet rays is irradiated with an energy density of W/-.

This operation can be performed, for example, by the apparatus shown in FIG. In the figure, 11 is a vacuum chamber, 12 is a gas inlet for introducing etching gas into the chamber 11;
Reference numeral 13 indicates a gas exhaust port for reducing the pressure within the chamber 11 to a predetermined pressure; 14 indicates a susceptor located within the chamber 11 on which the substrate 1 is placed; and 15 indicates a susceptor incorporated in the susceptor 14 for disposing the substrate 1.
16 is a window that maintains a vacuum in the chamber 11 and transmits the light 5, and 17 is a light source (mercury lamp) for the light 5.

Then, since the C12 etching gas is excited by the light 5, the first layer 2 is selectively etched only during the period when the light source 17 is turned on.

The reason why the temperature of the substrate 1 was set to 100°C is to make it easier to keep the temperature of the substrate 1 constant regardless of the irradiation of the light 5, in order to avoid changes in the etching rate due to changes in the temperature of the substrate 1. 1 if the temperature is kept constant.
It does not have to be 00°C.

Then, the etching area enters the area of the 20th layer 3 from the area of the opening 4, and after 5 minutes of lighting, the etching area becomes approximately 2.5 mm in diameter.
When turned on for 10 minutes, it becomes about 4.0mm in approximately 3μm circular shape.
It becomes 3 μm.

Therefore, in this side E/lamp, approximately 0.2 μm/
It can be seen that the etching speed is maintained at the same etching speed of 1000 yen, and it is also seen that the amount of side etching can be further increased by extending the lighting time.

The reason why the etching progresses so that the amount of side etching increases is that the 20th layer 3 transmits the light 5, and as mentioned above, the light 5 reaches the etching area and the side etching is progressing. This is because the etching gas near the etching surface is continuously excited. Figure 1 shows etching gas molecules,
Excited etching gas molecules and gas molecules produced by the etching reaction are indicated by circles, triangles, and holes, respectively.

Further, when we examined the etched product as described above, we found that the surface was clean and smooth, and no damage was found on the etched surface.

In the embodiment described above, the materials of the surface of the substrate 1, the 10th layer 2 and the second layer 3 are Si3N4 and S
t and 5 iOz, but if the etching gas is a combination that selectively etches the first layer 2, and the second W2B satisfies the conditions for transmitting the light 5 that excites the etching gas, the method of the present invention can be used. It is possible to implement

Further, although the example is a case where the second layer 3 has openings 4, it is easily understood that the method of the present invention is effective even if the second layer 3 has an arbitrary pattern shape. Good morning.

〔Effect of the invention〕

As explained above, according to the structure of the present invention, in the side etching of etching the first layer so as to enter the region of the second layer on the first layer from the exposed portion of the first layer, the side etching is performed. It is possible to increase the amount of etching, and to reduce damage to the etched surface while obtaining a clean and smooth surface, which has the effect of increasing the degree of freedom in designing, for example, semiconductor devices. ,

[Brief explanation of drawings]

Fig. 1 is a side view illustrating an embodiment of the method of the present invention, Fig. 2 is a side view of main parts of an example of an apparatus for carrying out the embodiment, Fig. 3 is a side view illustrating an example of a conventional method, and Fig. 4 is a side view illustrating an example of a conventional method. FIG. 2 is a side view illustrating an example of a conventional method. In the figure, 1 is the substrate, 2 is the first layer, 3 is the second layer, 4 is the opening, 5 is the excitation light, O is the etching gas molecule, △ is the excited etching gas molecule, and the opening is Gas molecules produced by the etching reaction, 11 a vacuum chamber, 12 a gas inlet, 13 a gas exhaust port, 14 a susceptor, 15 a heater, 16 a window, and 17 a light source. 6
The second squid is also a squid. ``Komo Ming 1 v Roy contract 'Ji Z co Figure 4

Claims (1)

[Claims] In a first layer on a substrate and a second layer on top of which a portion of the layer is exposed, the layer enters the area of the second layer from the exposed portion of the first layer. When performing side etching to etch the first layer, the second layer is made transparent, the substrate is placed in a gas that selectively etches the first layer by excitation, and the etching gas is A side etching method characterized by irradiating the substrate with light that excites the second layer from the side of the second layer.